Materials utilized for photovoltaic absorbers have become increasingly complex as those presently available are approaching their efficiency limits. In order to increase the efficiency of multi-elemental photovoltaic absorbers, the material is often graded in composition so that the energy gap (band gap) varies from the front to the back of the absorber in order to drive the electrons and holes more effectively toward their respective electrical contacts, and also to maximize absorption of sunlight.
In many materials, this compositional and/or elemental grading cannot be achieved because rapid diffusion of the elements in the absorber occurs during thermal processing. This problem affects not only photovoltaic devices but is a widespread problem in material science, since high temperature processing diffusively drives elements to undesired places.
Therefore, improved techniques for forming multi-elemental photovoltaic absorbers would be desirable.